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Data is waiting to become information. Through instrument interfaces, and data acquisition software you can transform raw data into useful information.
Computers and devices are equipped with a variety of inputs, and outputs. Inputs and outputs have both physical and virtual components. On the physical side, is the various ports, connectors, and cables utilized. On the virtual side, are the various protocols that operate over the physical interface. That said, physical interfaces aren’t limited to cabled connections. Wireless both radio frequency and optical are growing in popularity. Regardless of the physical medium most are digital, however some, such as audio, are analog.
Peripherals are not limited to monitors and keyboards. They also include sensors, and complex instruments. Each of these devices connects via some interface which could be wired or wireless. Be aware though, that a peripheral may be available in more than one interface type or may be equipped with multiple interface options. For example, monitors often equipped with both analog and digital inputs.
An input/output card expands a computer’s I/O options. These can range from a basic USB card, to a GPIB controller. Something to keep in mind, laptop computers tend to be more limited in their I/O expansion options. If you need more than USB and Ethernet capability, a desktop computer is recommended.
A bus technology allows multiple devices to share a common medium. With bus technologies, you can share a single port on your computer with multiple devices via a bus specific hub or in some cases via daisy chaining devices.
Hewlett-Packard Interface Bus evolved into the General Purpose Interface Bus. It’s a standardized interface bus used by a wide array of scientific instruments. One nice feature of GPIB, is the ease of converting it into another interface technology such as Ethernet or USB.
Ethernet is the most common network interface technology. So common, that most computers built today include Ethernet on-board. Many modern instruments have native Ethernet support, enabling them to be accessed directly from a desk, instead of via a computer located next to the instrument.
Serial and Parallel are both "legacy" interfaces. Their popularity has been in a decline over the past decade, largely being replaced with USB and Ethernet. Due to their decline, they aren’t typically seen on modern computers.
USB is a fairly universal bus technology. It’s used to connect everything from keyboards to GPIB interface controllers. It’s found on every computer made in the past 10 years, making it a safe choice when compatibility is needed.
Sensors exist for most everything, from temperature and pressure to particulate detection.
Hackable devices have become popular in the past few years. They are designed to make development of custom devices and sensor packages more accessible to a wider user base. In the past, where a commercially built sensor package would be used, a hackable system may be a suitable replacement.
GPS enables you to quickly and accurately determine location, altitude, and time. By integrating GPS into your field data acquisition, you may be able to partially automate location tracking of sensors and samples.
Mobile devices such as smartphones and tablets can be used for field data acquisition. They can be used to scan barcodes on sample containers and record the location (when equipped with GPS), or used to log notes during an interview.
Instruments require acquisition software. It translates the raw data from the instrument into a useful file format, or provides some additional processing capability. Keep in mind, some software and formats are limited to specific brands of instruments. So, be sure the software you wish to use will work with your equipment and other tools.
LabVIEW is a popular package due to it’s unique development language, called G. What sets G a part from others, is the graphical development model. Instead of writing pages of code, you graphically build your acquisition system by dragging and dropping objects on the screen.
ChemStation from Agilent is one of many chromatography packages. Like many instrument acquisition packages, it’s a vendor specific software package limited to use with Agilent equipment.
Torrent Suite is a modern sequence analysis package. It’s available with an open source license, making it free software. Open source alternatives exist for a variety of proprietary software.
Earlier we introduced the idea of "legacy interfaces" like serial and parallel, which are showing up on fewer and fewer computers these days. Which introduces a problem with both hardware and software used to interface with an instrument.
Let’s take for example a mid 90s vintage HPLC, which is likely to use GPIB to talk with the computer. While the basic GPIB interface is supported on a modern system, the instrument may have other requirements. Such as requiring manufacturer specific software that depends on their own interface card. And, the interface card uses the ISA bus, a bus that hasn’t been used in computers in almost 10 years.
So, why is this a problem? As the computer ages, it’s reliability goes down. In addition, it’s compatibility with peripherals and software becomes worse over time. Thus, while the instrument may still do it’s job, you may have difficulty transferring data from the computer to other systems, printing, etc. These issues may first appear as minor annoyances, but can quickly evolve into a work stoppage.
You can help to mitigate this situation, by reviewing the requirements for the instrument. For instruments that have a very long life, it’s best to avoid ones that depend on proprietary hardware interfaces. So, look for units that use USB or Ethernet. Review the software support policy, most manufacturers require you to purchase updates over time. But, make sure they have plans to support the instrument long term. In addition, you may want to see if any third-party software vendors support your instrument, as they have a greater financial interest in supporting older equipment.
Up until now, we’ve covered how instruments interface with a computer, software that interacts with the instrument, and the pitfalls of legacy systems. Now, we must turn our attention to the overall resource needs of instruments.
In a lab environment, it’s typical to have 1, maybe 2 instruments connected to a single computer. However, in the interest of saving money, and space some attempt to connect far more than that to a single computer. If the instruments aren’t being used simultaneously, you can probably get away with it. But, if you do wish to interact with many at once, you’re likely to run into issues.
One group actually attempted to connect a couple dozen instruments in a mobile environment to a single laptop computer. From a pure software perspective, their tool of choice, LabVIEW, is designed to interact with multiple devices at once. But, as the number instruments goes up, the amount of CPU, Memory, and Disk activity also goes up. That said, their main issue wasn’t with any of those resources, it was with interface technology. Each instrument connected via USB, which is a bus technology. And, like most bus technologies, the more devices on the bus, the slower it gets.
So, when developing a plan involving instruments that require a computer interface, you must consider more than just the physical connection, and the software support. You must also consider if the interface technology can really support that many active instruments at a time. In this example, the lab group ended up purchasing a second computer to divide up the work load.
To review. Peripherals are typically external input and output devices, such as keyboards, and monitors. There are a number of interface technologies on the market, the latest instruments can be purchased with Ethernet built-in, while most older devices will rely on GPIB. As for data acquisition, in the field you can use mobile devices like tablets, and GPS to aid your work. And, in the lab, use software like LabVIEW to process data from an instrument.
When purchasing lab instruments or working with older models keep a few things in mind. Older instruments may not work properly with modern computers. In some cases, the manufacturer may have a paid option to make it work, such as a software or interface upgrade. However, that option may be costly, so it’s best to plan ahead for that scenario, rather than be stuck trying to keep an old computer alive.
Finally, make sure your instrument needs, don’t exceed your computer and interface limitations. If you exceed those limits, you could face issues with reliable recording of data to possible hardware damage. Ultimately, planning ahead is likely to save time, and money.